Microalgal biorefinery for bulk and high-value products : Product extraction within cell disintegration

Microalgae are a promising source for proteins, lipids, and carbohydrates for the cosmetic, nutraceutical, chemical, food/feed, and biofuel industry. In comparison with soy and palm oil, microalgae can be produced in a more sustainable way. To make microalgae production economically feasible, all biomass ingredients need to be efficiently utilized, similar to petroleum refineries in which oil is fractionated in fuels and a variety of products with higher value. However severe conditions can affect the properties of some components in the biomass. To overcome this, focus needs to be put on biorefinery techniques which are mild and effective. Microalgal biorefinery is a linear process consisting of harvesting, cell disintegration, sequential extraction, and further fractionation. Among these steps, the cell disintegration often represents a bottleneck for the extraction of hydrophilic or hydrophobic components, due to the presence of a tough cell wall in many strains. State of the art knowledge on both novel and classical techniques for product extraction within cell disintegration is presented. Comparison is made on the basis of two main criteria: yield of disintegration and energy consumption. The current work gives also a comprehensive outlook on business cases for microalgae biorefinery